This invention relates to a hand using a low density material and a timepiece using the hand.
The conventional hands, generally, use brass material excellent in workability, strength and surface treatability as wristwatch hands. Consequently, brass material has a density as heavy as 8.5 g/cm3, and hand length width undergoes great restriction due to a drive force of a wristwatch mechanical movement.
Meanwhile, in the case a light-weighted hand is to be employed in relation to a drive force of a wristwatch mechanical movement, used is a two-bodied hand combining an engaging portion and a wing portion after separately fabricated.
The conventional hand, because using a brass material, is excellent in workability, strength and ornamentality. On the contrary, because the density is as heavy as 8.5 g/cm3, a great hand drive force is required where used on a timepiece. However, the timepiece needs to reduce hand drive force and decrease power consumption to a possible low extent, in order to prolong battery life. For this reason, the use of a conventional hand restricts a length or width of the hand. This has an effect upon viewability. As a result, there are an increasing number of pointing out of time illegibility by the aged persons and the like.
On the other hand, in case directly using an aluminum material having a density 2.7 g/cm3, a magnesium material having a density 1.8 g/cm3 or a resin material having a density 1.1 g/cm3 which are considered light-weighted, deformation occurs in the engaging portion because of absence of a material strength required for the hand. Consequently, hand deviation or disengagement takes place due to impact or the like. Meanwhile, for the conventional hand, it is to be considered to combine an engaging portion and a wing portion after separately fabricated (hereinafter, referred to as xe2x80x9ctwo-bodied handxe2x80x9d). The two-bodied hand tends to have increasing manufacturing cost for the hand itself. In the case of using a two-bodied hand, there additionally requires at least two parts for hour and minute hands. In the case of a multi-spindle hand, there are additional requirements corresponding to the number of spindles. Also, it will be expensive if assembling cost is included, and hence adoption is limitative.
Therefore, the invention is to solve the foregoing problem and to provide a hand having an integrated engaging and wing portions formed of a low density material not to cause hand deviation or disengagement. Due to this, even for a timepiece of a low power consumption type smaller in movement drive force, it is possible to use a longer hand or wider hand than the conventional, thus making possible to enhance viewability. Furthermore, much use of a light-storing material enables to enhance viewability furthermore.
Also, because of an integrated hand not requiring many parts, supply is feasible at a price unchanged from the conventional.
A hand of this invention comprising: a hand body having a wing portion for pointing a position and an engaging portion for engagement with a spindle of a movement, the wing portion and the engaging portion being integrally formed of a material having a density lower than a brass material; a first plating layer provided by making a plating on a surface of the hand body in order to improve strength after a substitution treatment; and a second plating layer provided by making a plating for ornament on the first plating layer.
Even if using a material having a density lower than a brass member (density 8.5 g/cm3) (hereinafter, referred to as xe2x80x9clow density materialxe2x80x9d), a hand can be integrally structured without making two bodies of a wing portion and an engaging portion. Due to this, a light-weighted hand can be provided.
In a hand of the invention, the first plating layer is either nickel plating or copper plating.
The use of nickel plating or copper plating can improve strength of the hand.
In a hand of this invention, the material of the hand body is of pure aluminum or an aluminum alloy. Due to this, a light-weighted hand can be provided.
In a hand of this invention, the material of the hand body is of pure magnesium or a magnesium alloy. Due to this, a light-weighted hand can be provided.
In a hand of this invention, the material of the hand body is of a resin material. Due to this, a light-weighted hand can be provided.
In a hand of this invention, the hand has the first plating layer having a plating total thickness, of plating to be made on the engaging portion, of 3 xcexcm or greater and 10 xcexcm or smaller. Due to this, a luster required as an ornament can be obtained.
A timepiece of this invention uses the foregoing hand. By using such a hand on a timepiece, a long or wide hand can be attached even on a timepiece smaller in hand drive force. In particular, because even a small-sized movement can use a large-sized hand, viewability can be improved.